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Study finds exercise reduces breast cancer recurrence

What was the aim of the study?

The study, published in the Canadian Medical Association Journal, reviewed research conducted in the past 10 years on breast cancer recurrence and lifestyle factors to determine which changes can reduce the chance of breast cancer recurrence and death. Lifestyle changes included exercise, weight management, particular dietary changes, quitting smoking, reducing alcohol consumption and vitamin supplementation.

What were the results?

The review found that of the different lifestyle changes, exercise had the biggest effect on reducing the risk of breast cancer recurrence and death. In most studies, this effect was present regardless of the level of activity before the cancer diagnosis. The review also found that women who gained weight during or after breast cancer treatment were shown to be at higher risk of breast cancer recurrence and death. There are currently no clear indications of whether weight loss or the prevention of further weight gain helps prevent breast cancer recurrence, but a number of studies investigating this are currently underway.

No particular diet has been shown to reduce breast cancer recurrence and soy products have not been found to increase breast cancer recurrence. While more evidence is required, taking moderate amounts of vitamin C supplements may be helpful. It is not clear as to whether quitting smoking affects breast cancer recurrence but as it reduces the risk of other smoking-related illnesses it is worthwhile. While the results of alcohol consumption and breast cancer recurrence are inconclusive, limiting alcohol consumption to one or fewer drinks per day may reduce the risk of a second breast cancer.

What do the experts say?

The authors explain that of “all lifestyle factors, physical activity has the most robust effect on breast cancer outcomes … Because it is common for patients to reduce their level of physical activity after a breast cancer diagnosis, it is important for health care professionals to promote and encourage exercise in this patient population.”

What do the results mean for women with breast cancer?

Women diagnosed with breast cancer are often concerned with what they can do to reduce the risk of their breast cancer returning. The results from this review give these women practical advice on where they can make the most difference. For example, following the recommended 150 to 300 minutes of moderate intensity physical activity or 75-150 minutes of vigorous intensity physical activity (or an equivalent combination of both) each week is one of the most important steps that women can take to reduce their chances of breast cancer recurrence and death. Women should aim to include muscle strengthening activities on at least two days a week.

It can be difficult for women to maintain physical activity during breast cancer treatment due to fatigue or other treatment related side effects. However, the results from this study show the importance of trying to keep some level of activity up. If women are going to choose any lifestyle changes then this is the best option.

Importantly, the study authors caution that lifestyle changes “cannot always improve outcomes of cancer with particularly aggressive biology. Patients should not be made to feel that inadequate lifestyle changes have led to their cancer recurrence.”